Question

A water sample from a hot thermal vent contained a single-celled organism that had a cell wall and a nucleus. classify this cell. selected:
a. prokaryotethis answer is incorrect.
b. eukaryote
c. bacteria
d. plant

Answer 1

The correct answer is a eukaryote. While it would be an impulse to answer prokaryote since the first thing that will come to our minds if we deal with a microorganism that thrives in extreme environments (i.e. hot thermal vents) will be archea, which are prokaryotes. But in this case, it is clearly specified that the single-celled organism has a nucleus which is the characteristic feature of eukaryotes. 

Bacteria is incorrect as bacteria are prokaryotes. Plant is incorrect as all plants are multicellular organisms.